Post-traumatic stress disorder (PTSD) and its consequences place a large burden on the public and on the individuals who suffer from it, yet the clinical evaluation of PTSD is limited by its dependence on the subjective self-report of patients. Physiological monitoring would be useful to researchers and therapists, particularly during the patient's daily life. Psychophysiological markers could be used to evaluate and tailor individual patient treatment and to tell patients when and how to relax. Furthermore, physiological parameters could help determine who is at risk for developing PTSD after traumatic events facilitating early intervention. Several studies have demonstrated that PTSD is associated with changes in various physiological parameters; however, current tools are too cumbersome and cannot feasibly monitor these parameters during a patient's everyday life. Successful development and commercialization of an ambulatory PTSD monitor could lead to improved patient treatment, faster recovery, and reduced healthcare costs. The overall goal of this multi-phase SBIR project is to develop, validate and commercialize an ambulatory PTSD monitor that can measure relevant physiological parameters for long periods of time without disrupting the patient's life. In addition to integrating multiple parameters into a compact wearable device, the device will incorporate sensor and algorithm intellectual property for improved signal to noise ratio. Preliminary research from Aclaris Medical sets the stage for successfully meeting the following Phase I aims to demonstrate feasibility: 1) Complete bench concept prototype, 2) Complete human evaluation of bench concept, and 3) Complete integrated prototype. The research team, led by Mark Bly, has successfully developed and commercialized ambulatory monitors for arrhythmia detection and heart failure patient monitoring in the past. Roger K. Pittman, MD; Scott P. Orr, PhD; Mark S. Greenberg, PhD; Jean C. Beckham, PhD; and Walton T. Roth, MD, experts in psychophysiological monitoring, will provide clinical advisement. The prototype made available by completion of the Phase I milestones will be able to collect a data set that has not been possible to date. The simplicity and tolerability of the proposed device will enable months of monitoring, improved compliance, and easier trial enrollment that can lead to advancements in PTSD research, screening, and treatment. The prototype will be refined, subjected to final testing, and employed in PTSD clinical research in Phase II. FDA approval will also be sought by Aclaris Medical in parallel to Phase II clinical activities. In Phase III, the company will seek to commercialize the device for mental health clinical research, particularly involving PTSD. Clinical research is expected to lead to larger commercial opportunities for the device such as the routine screening, monitoring, and treatment of PTSD or other mental health disorders and conditions, including panic disorder, phobias, generalized anxiety disorder, depressive disorders, and overall life stress.